[ES6 modules] Introduce Modulator::Fetch{Tree,TreeInternal,Single}

third_party/WebKit/Source/core/dom/AncestorList.h

Index: third_party/WebKit/Source/core/dom/AncestorList.h
diff --git a/third_party/WebKit/Source/core/dom/AncestorList.h b/third_party/WebKit/Source/core/dom/AncestorList.h
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index 0000000000000000000000000000000000000000..1eb020e90364098db6d84ffe27d3988ca1367c57
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+++ b/third_party/WebKit/Source/core/dom/AncestorList.h
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+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef AncestorList_h
+#define AncestorList_h
+
+#include "platform/weborigin/KURL.h"
+#include "platform/weborigin/KURLHash.h"
+#include "platform/wtf/HashSet.h"
+
+namespace blink {
+
+// Maps to "ancestor list" concept referenced in multiple module script
+// algorithms.
+// Example:
+// https://html.spec.whatwg.org/#internal-module-script-graph-fetching-procedure
+using AncestorList = HashSet<KURL>;
+
+}  // namespace blink
+
+#endif